1. Field of the Invention
The invention relates to a welding method, and more particularly to a through hole welding method.
2. Description of the Related Art
In industrial production, a metal or an alloy is usually molten to combine with or adhere to another metal. However, most metals, particularly in the molten state, are easily oxidized. In general, a reducing agent is employed to prevent the oxidization of the molten metal, and the reducing agent includes a reduction powder, a reduction metal, and a viscous gel reduction substance. However, the reducing agents have the following defects.
1) The reduction powder is inconvenient for use and easily flies apart, and much smoke is produced, which is difficult to discharge and treat, thereby causing environmental pollution.
2) The reduction metal has high material cost and processing cost; the addition amount of the reduction metal is difficult to control, and the use of an overdose of the metal particle may increase the tension of the molten alloy.
3) The viscous gel reduction substance has low diffusion efficiency thereby requiring laborious stirring, and high viscosity thereby being difficult to clean. The mixture of viscous residues and the molten metal often blocks the technological equipment.
In addition, the molten solder obtained from the above methods has relatively high oxygen content, thereby affecting the welding quality.